Define touch voltage and step voltage and describe how to mitigate each.

• A. Touch voltage is the voltage difference a person experiences when touching a conductive part and ground; step voltage is the difference between voltages at two feet; mitigate with proper grounding, barriers, insulation, and safe distances.
• B. Touch voltage is the voltage between live parts; step voltage is the voltage between ground and air.
• C. Touch voltage is the potential difference in the panel; Step voltage is the same as touch voltage.
• D. Touch voltage and step voltage are the same and cannot be mitigated.

Answer: (A)

Touch voltage is the potential difference a person experiences between a live conductive surface they touch and the ground. When you grab or contact an energized part and your body provides a path to earth, current can flow through you, driven by the voltage between the part you’re touching and the ground you stand on. Step voltage is the potential difference between the ground at two places where your feet are, which can happen when a fault causes current to spread through the earth. The earth isn’t at the same voltage everywhere, so the surface under one foot can be at a different potential than the surface under the other foot, and that difference can drive current through the legs.

To mitigate touch voltage, ensure exposed conductive parts are properly grounded and bonded to a low-impedance earth, use barriers or enclosure to prevent contact, and employ insulation or guarding where contact could occur. Safe distances and appropriate protective devices also help keep energized parts separated from people.

To mitigate step voltage, create an equipotential path around the hazard by bonding conductive surfaces and installing an effective grounding grid so ground potential is as uniform as possible. Use barriers or fences to restrict access to the hazard area and consider insulating mats or footwear where exposure is possible. Quick fault interruption and proper design of the grounding system reduce the energy available, further lowering the risk from stepping across a potential difference.

Other definitions mix up what constitutes touch versus step voltage or claim they’re the same, which doesn’t fit how the voltages arise or how they’re best controlled.